refactor(core): Use an IoC container to manage singleton classes [Part-2] (no-changelog) (#5690)

* use typedi for UserManagementMailer

* use typedi for SamlService

* fix typos

* use typedi for Queue

* use typedi for License

* convert some more code to use typedi

packages/cli/src/UserManagement/email/UserManagementMailer.ts

@@ -2,13 +2,9 @@ import { existsSync } from 'fs';
 import { readFile } from 'fs/promises';
 import Handlebars from 'handlebars';
 import { join as pathJoin } from 'path';
+import { Service } from 'typedi';
 import config from '@/config';
-import type {
-	InviteEmailData,
-	PasswordResetData,
-	SendEmailResult,
-	UserManagementMailerImplementation,
-} from './Interfaces';
+import type { InviteEmailData, PasswordResetData, SendEmailResult } from './Interfaces';
 import { NodeMailer } from './NodeMailer';
 
 type Template = HandlebarsTemplateDelegate<unknown>;
@@ -36,8 +32,9 @@ async function getTemplate(
 	return template;
 }
 
+@Service()
 export class UserManagementMailer {
-	private mailer: UserManagementMailerImplementation | undefined;
+	private mailer: NodeMailer | undefined;
 
 	constructor() {
 		// Other implementations can be used in the future.
@@ -81,12 +78,3 @@ export class UserManagementMailer {
 		return result ?? { emailSent: false };
 	}
 }
-
-let mailerInstance: UserManagementMailer | undefined;
-
-export function getInstance(): UserManagementMailer {
-	if (mailerInstance === undefined) {
-		mailerInstance = new UserManagementMailer();
-	}
-	return mailerInstance;
-}